Speed governor for sewing machine motors



y ,5 c. H. SPARKLIN 2,516,156

SPEED GOVERNOR FOR SEWING MACHINE MOTORS Filed July 20, 1945 2Sheets-Sheet 1 July 25, 1950 c. H. SPARKLIN 2,515,156

SPEED GOVERNOR FOR SEWING MACHINE MOTORS Filed July 20, 1945 2Sheets-Sheet 2 Patented July 25, 1950 SPEED GOVERNOR FOR SEWING MACHINEMOTOR Charles H. Spar-kiln, Chicago, Ill., assignor to Birtman ElectricCompany, a corporation of Illinois Application July 20, 1945, Serial No.606,076

7 Claims.

on small motors, like a'sewing machine motor.

They are inefilcient over a wide range of speed values, and the rangeover which they operate is oftentimes not great enough to give thedesired broad range.

I have invented a speed control for sewing machine motors that isefllcient over a wide range of speeds, yet is simple in construction andlight in weight. This new apparatus is small, so that it can iltinto alimited space, and is provided with means for easily changing the speedof the motor. The new and improved speed control includes the speedgovernor and means for varying the operation of the governor at a remotepoint. The new control is especially adaptable for sewing machine motorsin that it is light in weight, of mall construction, and is equallyefficient over a wide range of speed values.

The invention will be described as related to the embodiment set out inthe accompanying drawings. of the drawings, Fig. 1 is an elevationpartially broken away, showing the new speed control for a sewingmachine motor; Fig. 2 is a view taken along line 2--2 of Fig. 1; Fig. 3is an elevation, partially in section, of a sewing machine motor andattached speed governor; Fig. 4 is a section taken along line I of Fig.3; Fig. 5 is a section taken along line 5 of Fig. 3; and Fig. i5 is asection taken along line 6-8 of Fig. 4.

The speed control includes a speed governor in mounted adjacent a sewingmachine motor I i. The governor and motor are preferably of the samediameter, so that one appears to be merely an extension of the other, asshown in Figs. 1 and 3. The motor H has a shaft l2, on one end or whichis mounted a friction wheel l3 for operating the drive wheel ll of asewing machine It. The speed governor it, which is shown mounted on theopposite end of the motor, is preferably constructed like the speedgovernor set out in my copending application Serial No. 580,114, filedFebruary 28, 1945. A full and complete description of the speed governoris given in the application cited hereinabove.

The end of the motor shaft l2 opposite the 2 end upon which the flangewheel I! is mounted extends beyond the motor. Upon this end of the shaftis mounted a pair of parallel plates i6 arranged for rotation with theshaft. These plates are held in their parallel relationship by means ofa plurality of studs l'l passing through the plates. On two of thesestuds there are located a pair of centrifugally responsive arms l8,fulcrumed at one end. As the plates i6 rotate, these arms move outwardunder the action of centrifugal force. Bearing against these arms aretwo bell cranks i9 arranged so that both legs of each bell crank liesubstantially within the confines of the rotatable plates IS. These bellcranks are arranged so that each arm I8 bears against one leg of thebell crank as the arms move outward under centrifugal force. Eachnon-contacting leg of the bell cranks bears against a second bell crank20 mounted on the plates l6 and substantially at right angles thereto.The free ends of the second bell cranks 20 extend toward the shaft i2and are in contact with the bottom of a slideable cylinder 2i mounted onthe shaft l2.

The end of the slideable cylinder 2|, which is opposite the rotatableplates, passes through a hole 22 in one arm 23 of a contact switch 24,and pushes against a bearing piece 25 on the other switch arm 25.

The switch 24 is held closed by means of a spring 21 operating on thetwo parallel arms of the switch. These switch arms are mounted forrotation around a fulcrum 28, and the spring 21 is preferably located atthis point. The contact point 29 are held in closed position by means ofthis fixed spring 27, and the bearing piece 25 is held against theslideable cylinder 2| by means of a variable spring 30.

The switch arm 23, through which the slideable cylinder 2! passes, hasan extension 3i extending beyond the fulcrum 28, around which the switchis mounted for movement. A bearing member 32 presse against the end ofthe extension 3| and serves to position the switch about its fulcrum.This bearing member 32 is provided with screw threads 33 that mesh withscrew threads in a fixed mounting 34. The bearing member 32 extendsbeyond the fixed mounting and has a smooth end bearing against theswitch arm extension 3l. The other end of the bearing memher is finishedin a flat plate 35. Attached to the fixed mounting 34 at the endopposite the bearing member is a flexible cable 36, mounted for axialrotation. This cable is attached to a fitting i'l extending into themounting and terminating in a cylindrical member 38 which has an axialgroove 39 at its inner end for engagement with the flat plate 35. Thisconstruction is provided so that as the cable 36 is revolved the endfitting 31 turns the bearing member 32 and screws it in and out of thefixed mounting 34, thereby moving thefiat plate back and forth in thegroove 39. i

The flexible cable 36 extends to a point remote from the speed controland the motor. At this end of the cable there is positioned a piniongear 40, which is engaged by a toothed sector 4|. This toothed sector 4|forms a part of an arm 42 mounted for rotation around a fulcrum 43. Inthe construction shown the pinion gear 40 is mounted on a flat plate 44that is attached to the underside of a table 45, upon which the sewingmachine, motor, and speed governor are mounted. This flat plate 44 isarranged vertically by being attached to a vertical side of the table. Asecond flat plate 46 is arranged parallel to the first plate 44 andspaced therefrom. The end of the flexible cable 35 passes through thissecond plate 46, and the pinion gear 40 is located between the plates..The arm 42, which forms an extension of the toothed sector 4|, is of agenerally semicircular shape, with the toothed sector at one end and thefulcrum 43 at the opposite end. Mounted on this armin adownwardlyextending position is a lever 41 for operating the control mechanism.This lever is bolted at one end through a slot 48 provided in the arm 42so that it can be readily positioned in the slot by thumb screw 49. Inorder to limit movement of the arm 42 there is provided a stud 50extending through an arcuate slot in the second flat plate 46. Thecurved arm 42 is held in a position corresponding to slow motor speed bymeans of a spring 52 attached to the arm and to the second flat plate46.

When the speed control is set for any given speed the rotatable platesI6 rotate with the motor shaft l2.- This causes the movable arms l8 tomove outwardly under the influence of centrifugal force set up in thesearms. speed increases these arms l8 move out further under the increasedcentrifugal force. This movement causes bell cranks I! to move aboutWhen the their fulcrums and operate second bell cranks 20.

The free arms of the second bell cranks push out on the cylindricalfitting 2|, and when the speed becomes great enough, pushes switch arm25 away from switch arm 23, and breaks the electrical circuit to themotor by separating the contact points 29. The contact points are heldin normally contacting relationship by means of the fixed spring 21 andthe variable spring 30. The structure and purpose of these two springsare set out in detail in my copending application cited hereinabove.

When it is desired to change the setting of the speed control theoperator of the sewing machine moves lever 41 with her knee. This causesthe toothed sector 4| to locate the flexible cable 36 and position thebearing member 32 within its fixed mounting 34. The position of thebearing member bears against the extension 3| to the first switch arm23, and thereby determines the position of the switch 24 relative to therotatable plates it. As can be seen, this relative position of theswitch is what determines the speed at which the motor operates.Whenever it is desired to change the speed of the motor, it is onlynecessary to move the lever 41.

From the foregoing description it can be seen that the speed control isreadily adjustable to provide any speed desired over the operatingrange. This operating range in one installation set out in my copendingapplication is from 618 R. P. M. to 6790 R. P. M.

This invention has been described in considerable detail as related toone embodiment of the same. It is to be understood, however, that theinvention is not to be limited by these details unless otherwisespecified, but rather be construed broadly within its spirit and scopeas set out in the accompanying claims.

I claim:

l. A speed control comprising a rotatable member arranged for rotationin a substantially fixed plane, means for rotating said member, anelectric switch mounted on a fulcrum for ready movement to position saidswitch relative to said rotatable member, said switch including an armextending beyond the fulcrum, means operable by the rotation of saidrotatable member for breaking contact of said switch when the speed ofrotation exceeds a predetermined value, with this predetermined speedbeing dependent upon the position of the switch relative to therotatable member, a threaded bearing member bearing against saidextended switch arm and held in a similarly threaded fixed mounting, aflexible cable leading from the bearing member to a point remote fromthe speed control, a pinion'gear mounted on the end of the flexiblecable, a toothed sector in engagement with the pinion gear with thesector forming a part of an arm mounted on a fulcrum, and means urgingsaid sector arm toward a low speed position.

2. A speed control comprising a rotatable member arranged for rotationin a substantially fixed plane, means for rotating said member, anelectric switch mounted on a fulcrum for ready movement to position saidswitch relative to said rotatable member, said switch including an armextending beyond the fulcrum, means operable by the rotation of saidrotatable member for breaking contact of said switch when the speed ofrotation exceeds a predetermined value, with this predetermined speedbeing dependent upon the position of the switch relative to therotatable member, a threaded bearing member bearing against saidextended switch arm and held in a similarly threaded fixed mounting, aflexible cable leading from the bearing member to a point remote fromthe speed control, a pinion gear mounted on the end of the flexiblecable, a toothed sector in engagement with the pinion gear with thesector forming a part of an arm mounted on a fulcrum, and a leverrigidly fixed to the arm for movement thereof about the fulcrum.

3. A speed control comprising a rotatable member arranged for rotationin a substantially fixed plane, means for rotating said member, anelectric switch mounted on a fulcrum for ready movement to position saidswitch relative to said rotatable member, said switch including an armex tending beyond the fulcrum, means operable by the rotation of saidrotatable member for breaksector in engagement with the pinion gear withthe sector forming a part of an arm mounted on a fulcrum, and a leverfixed to the arm for movement thereof about the fulcrum, the pitchdiameter of the toothed sector being considerably greater than the pitchdiameter of the pinion gear so that twist effect of the flexible cableis negligible.

4. A speed control comprising a rotatable member, means for rotatingsaid member, an electric switch comprising a pair of arms arranged sideby side spaced from therotatable member and arranged approximately atright angles to the axis of rotation of the rotatable member, said armshaving cooperating contact members at one of the ends of the arms andbeing mounted for rotational movement about a fulcrum at the other endsof the arms, with said movement being toward and away from the rotatablemember, means operable by rotation of said rotatable member for breakingcontact between said contact members when the speed of rotation of therotatable member exceeds a predetermined value with said value beingdependent upon the distance between the switch and the rotatable member,an arm forming a part of said switch and extending beyond the fulcrum, abearing member normally contacting said arm and having at least aportion of its surface threaded, a fixed mounting member in which thebearing member is held with the mounting member having similar threadsengaging those of the bearing member, a flexible cable leading to apoint remote from the bearing member and being attached to the bearingmeber to rotate it when said cable is rotated about its axis, a piniongear mounted on the end of the cable and fixed for rotation about anaxis coinciding with the axis of the cable, a sector arm mounted forrotation about a fulcrum at one end having teeth on its opposite endengaging the pinion gear, said teeth being located on the arc of acircle whose center is substantially at the fulcrum, and a. second armhaving one end rigidly fixed to the sector arm and extending away fromthe sector arm.

5. A speed control comprising a rotatable member, means for rotatingsaid member, an electric switch comprising a pair of arms arranged sideby side spaced from the rotatable member and arranged approximately atright angles to the axis of rotation of the rotatable member, said armshaving cooperating contact members at one of the ends of the arms andbeing mounted for rotational movement about a fulcrum at the other endsof the arms, with said movement being toward and away from the rotatablemember, means operable by rotation of said rotatable member for breakingcontact between said contact members when the speed of rotation of therotatable member exceeds a predetermined value with said value beingdependent upon the distance between the switch and the rotatable member,an arm forming a part of said switch and extending beyond the fulcrum, abearing member normally contacting said arm and having at least aportion of its surface threaded, a fixed mounting member in which thebearing member is held with the mounting member having similar threadsengaging those of the bearing member, a flexible cable leading to apoint remote from the bearing member and being attached to the bearingmember to rotate it when said cable is rotated about lts axis, a piniongear mounted on the end of the cable and fixed for rotation about anaxis coinciding with the axis of the cable, a sector arm mounted forrotation about a fulcrum at one end and having teeth on its opposite endengaging the pinion gear, said teeth being located on the arc of acircle whose center is substantially at the fulcrum, and a second armhaving one end rigidly fixed to the sector arm and extending away fromthe sector arm, said second arm being attached to the sector arm at apoint between the fulcrum end and the teeth end.

6. A speed control comprising a rotatable member, means for rotatingsaid member, an electric switch comprising a pair of arms arranged sideby side spaced from the rotatable member and arranged approximately atright angles to the axis of rotation of the rotatable member, said armshaving cooperating contact members at one of the ends of the arms andbeing mounted for rotational movement about a fulcrum at the other endsof the arms, with said movement being toward and away from the rotatablemember, means operable by rotation of said rotatable member for breakingcontact between said contact members when the speed of rotation of therotatable member exceeds a predetermined value with said value beingdependent upon the distance between the switch and the rotatable member,an arm forming a part of said switch and extending beyond the fulcrum, abearing member normally contacting said arm and having at least aportion of its surface threaded, a fixed mounting member in which thebearing member is held with the mounting member having similar threadsengaging those of the bearing member, a flexible cable leading to apoint remote from the bearing member and being attached to the bearingmember to rotate it when said cable is rotated about its axis, a piniongear mounted on the end of the cable and fixed for rotation about anaxis coinciding with the axis of the cable, a sector arm mounted forrotation about a fulcrum at one end having teeth on its opposite endengaging the pinion gear, said teeth being located on the arc ot'acircle whose center is substantially at the fulcrum, and a second armhaving one end rigidly fixed to the sector arm and extending away fromthe sector arm, said second arm being attachable to the sector arm atany one of a plurality of points between the fulcrum end and the teethend.

7. A speed control comprising a rotatable member, means for rotatingsaid member, an electric switch comprising a pair of arms arranged sideby side spaced from the rotatable member and arranged approximately atright angles to the axis of rotation of the rotatable member, said armshaving cooperating contact members at one of the ends of the arms andbeing mounted for rotational movement about a fulcrum at the other endsof the arms, with said movement being toward and away from the rotatablemember, means operable by rotation of said rotatable member for breakingcontact between said contact members when the speed of rotation of therotatable member exceeds a predetermined value with said value beingdependent upon the distance between the switch and the rotatable member,

an arm forming a part of said switch and extending beyond the fulcrum, abearing member normally contacting said arm and having at least aportion of its surface threaded, a fixed mounting member in which thebearing member is held with the mounting member having similar threadsengaging those of the bearing member, a flexible cable leading to apoint remote from the bearing member and being attached to the bearingmember to rotate it when said cable is rotated about its axis, a piniongear mounted on the end of the cable and fixed for rotation about anaxis coinciding with the axis of the cable, a sector arm mounted forrotation about a fulcrum at one end having teeth on its opposite .endengaging the pinion gear, said teeth being located on the arc of acircle whose center is substantially at the fulcrum, and a second armhaving one end rigidly fixed to the sector arm and extending away fromthe sector arm, said second arm being attachable to the sector arm atany one of a plurality of points between the fulcrum end and the teethend, and means for urging the sector arm toward a low speed positionwhen no force is applied to said second arm.

CHARLES H. SPARKLIN.

REFERENCES CITED The following references are of record in the file ofthis patent:

Number Number 15 7,276

8 UNITED STATES PATENTS Name Date Griep Jan. 10, 1911 Lee June 24, 1930Oldham Nov. 19, 1935 Grantham Aug. 22, 1939 Taylor Jan. 30, 1940 SauppApr. 2, 1940 Lawson Dec. 31, 1940 Schmitt et a1. Dec. 21, 1943 Lee July11, 1944 FOREIGN PATENTS Country Date Great Britain Mar. 26, 1909 GreatBritain Jan. 25, 1934

